Driving mechanism for slide in a press



DRIVING "MECHANISM FOR SLIDE IN A PRESS Filed Aug 9 1968 2 Sheets-Sheet 1 DEGREES m om: CYCLE B (PRlOR CRANK PRESS) DIS PLACEMENT SUKENAOYQSHIDA ETAL 3,508,451 DRIVING MECHANISM FOR SLIDE IN A PRESS April 28, .1970

2 sheets -sheet 2 Filed Aug. 9, 1968 United States Patent O US. Cl. 74-394 Claims ABSTRACT OF- DISCLOSURE I A driving mechanism for the'slide in a press comprising a slide driving main gear freely mounted on a maincrank shaft journalled in the frame of said press, a drive gear fixedlymounted on a main drive shaft and in engagement with said main gear, an auxiliary crank shaft journalled in said main gear, a planetary gear fixedly mounted on said auxiliary crank shaft and a sun gear fixedly supported in said frame in a concentric relation to said main crank shaft and in engagement with said planetary gear, said auxiliary crank shaft having a crank pin which is connected through a link to the fixed arm of said main crank shaft.

BACKGROUND OF THE INVENTION Therefore, the material drawing rate by such a prior art press is inevitablylimited within a relatively low value range. Thus, the prior art press has to be necessarily so designed that the number of strokes of the slide per minute is determined depending upon the length of the stroke of the slide movement in a cycle of operation and the number of strokes of the slide per minute is increased only by causing the slide to move describing a non-cosine curve in which the velocity of the slide is increased both in a stroke portion descending from the upper dead point to a point adjacent to the middle in .its descending strokeand in the non-productive stroke portion ascending from the lower dead point to the upper dead point.

SUMMARY OF THE INVENTION The present invention relates to an improved driving mechanism for the slide in a press and more particularly, to an improved driving mechanism for the slide in a press for sheet metal in which the driving mechanism drives the slide toward a material to be processed at a high velocity and also to return the slide at a similarly high velocity after the performance of processing upon the material by the die carried in the slide at a low rate. v

' One object of the present invention is to provide an improved driving mechanism for the slide in a press whereby the number of strokes of the slide per minute can :be substantially-increased while maintaining the prtfcessing rate of the press at a predetermined constant va ue. Y

Another object of the present invention is to provide an improved driving mechanism for the slide in a press whereby the setting of various different stroke lengths can be more easily made as compared with the setting by the prior art quick returning mechanism.

3,508,451 Patented Apr. 28, 1970 ice A further object of the present invention is to provide a simplified and compact driving mechanism for the slide in a press.

According to the present invention, there is provided a driving mechanism'for the slide in a press comprising a main crank shaft rotatably journalled in the frame of said press for driving said slide, a main gear freely mounted on said main crank shaft, a driving shaft journalled in said frame and having a fixed drive gear in engagement with said main gear for driving the latter, an auxiliary crank shaft journalled in said mean gear, a planetary gearfixedy mounted on said auxiliary crank shaft and a' sun gear fixedly supported in said frame in a concentric. relation with said main crank shaft for engagement with said planetary gear, a crank pin of said auxiliary crank shaft being connected by means of a link to a fixed arm of said main crank shaft. 1

. The above and other objects and attendant advantages of the present invention will be more readily apparent BIRIEF DESCRIPTIONS OF THE DRAWINGS FIG. 1 is a graph which compares the novel slide driving mechanism with a prior art slide driving mech anism by graphically showing the curves of the slide displacement and velocity characteristics obtained by both the novel and prior art slide driving mechanisms respectively;

FIG. 2 is a fragmentary vertical section view of essential parts of a preferred form of press slide driving mechanism constructed in accordance with the present invention showing a portion thereof in section taken along the line 11-11 of FIG. 3; and

FIG. 3 is a cross-section view taken along the line III'III of FIG. 2.

Referring to FIG. 2 of the accompanying drawings in which a preferred form of press slide driving mechanism by the present invention is shown as being incorporated in a press for driving the slide of the press, the press generally comprises a machine frame 1 in which a main crank shaft 2 is rotatably mounted in a conventional manner by means of conventional bearings and the crank shaft has a crank pin 2' which is connected through a conventional connecting rod 3 to a conventional slide S which carries die therein (not shown) in a conventional manner. The crank shaft 2 further has an arm 4 connected thereto by means of a spline arrangement as shown at 4. The free end of the arm 4 has one end of a link 6.

connected thereto by means of a transverse pin 5 and the other end of the link is connected to the crank pin 7 of an auxiliary crank shaft 7 which is in turn secured at one end to the shaft 8' of a planetary gear 8 which is.

to the main crank shaft 2 as shown in FIG. 3 (the plane-.

tary gear 8 is shown as being separated from the sun gear 9 for clarification of showing in FIG. 2). A drive pinion 11 is fixedly mounted on one end of a main drive shaft 12 and the pinion is in engagement with the main gear 10. The drive shaft 12 is adapted to be driven from a conventional driving source (not shown) through a pulley 12 and a clutch (not shown) mounted on the other end of the shaft 12. v

The drive shaft 12 is adapted to rotate at a predetermined constant rate as the driving source is operated and 3 accordingly, the drive shaft 12 actuates to rotate the main gear 10 by virtue of the engagement between the pinion 1 1 and main gear 10.. As the main gear 10 is rotated in the manner as mentioned just above, the planetary gear 8 rotates about its own axis while revolving about the, sun gear 9 by virtue of the engagement between the-planetary and sun gears. Assuming that the planetary gear S-and sun gear have the same number of teeth, then, the plane: tary gear 8 completes about its axis two rotations each time the main gear '10 completes about its own axis" one rotation. Therefore, the auxiliary crank-shaft 7 connected to the shaft 8 of the planetary gear 8 completes about its axis two rotations, each time the main gear 10 completes about its axis one rotation. In otherwords, the auxiliary crank shaft 7 rotates atthe equi-angular rate. However, when this equiangular rotational movement of the auxiliary crank shaft 7, is considered from the axisof the main crank shaft- 2,. since the rotational movement of the auxiliary crank shaft 7 is transmittedthroughthelink 6, pin and the arm 4 of the main crank shaft 2. to the main crank shaft,.the equi-angular rotational movement of the auxiliary crank shaft 7 comes to appear as an equiangular rotational movement added a crank lever movement of the so-called quadribar mechanism.

From the foregoing equi-angular rotational movement of the auxiliary crank shaft 7 as mentioned just above, it will be understood that even if the main gear rotates in the equi-angular rotational movement, such movement of the main gear 10 is transmitted to the main crank shaft Z as an inequiangular rotational movement whereby the main crank shaft 2 drives the slide S.-As a result of the driving of the slide in the above manner, the displacement curves and velocity curves of the slide which are shown as A and B, respectively in FIG. 1 are obtained. FIG. 1 comparatively shows the displacement and velocity characteristics of the slide which are obtained by the slide driving mechanism of the present invention and those of the slide which are obtained by a prior art slide driving.

ZlEViCe or crank mechanism in order to manifest the advantages of the present invention over those of the prior art device.

Referring to FIG. 1 of the accompanying drawings, :he curves of this figure have been plotted on the assump- :ion that the actual operation rate of the illustrated press ilide when the same is driven by the novel driving mechanism is the same as that of the same type-slide when the ;lide is driven by the prior art crank mechanism. In this igure, the curves shown with reference characters a and b ienote the displacement and velocity characteristics of the press slide obtained by the prior art crank mechanism while the curves shown with reference characters A and B lenote the displacement and velocity characteristics of :he slide obtained by the novel driving mechanism. As inderstood from the illustration in this figure, according o the present invention the period of non-productive or dle time in a cycle, that is, the time period during which he press performs non-productive operation is substan- :ially shorter than that in a cycle of operation by the )ress which employs the prior art crank mechanism as he driving means for the slide. To conversely speak, it neans that if the time required for a cycle is the same 11 both the systems, the press can be operated at a slower irawi ng rate according to the present invention.

One of the most important difiiculties in the, fabricaion of a press'or a press system comprising a plurality )f presses arranged in alignment. in which the slide disalaces describing .a cosine curv elis that the number of :trokes of the slide per minute is restricted to a certain Ialueby the drawing press; Therefore, in order to in- :r ease the number of the strokes per minute in the entire.

ress system, it is necessary to increase the number of .t'roke s per minute in the drawing: press.

The present invention is, therefore, to eliminate the lifiiculty inherent in the prior art press or press system nentioned just above.

. According to the present invention, as shown in FIG..1 by the curves A and B, assuming that the descending velocity of the slide at the point at which the press initiates the actual productive operation is the same as that in a conventional press, the time required for a cycle of operation can be reduced to less than one-half of that required in the conventional press. In other words, while in'the corresponding conventional pres's onlyle'ss' than one-quarter of "a cycle time by the conventional slide driving mechanism in the form offa crank mechanism was utilized for actual processing, in the press employing the novel drive mechanism a substantial tinieas much as about four-ninths of a cycle can be utilized for actual productive operation. U

Furthermore, according to the present invention, as mentioned above, the slide driving main crank shaft is driven from the main drive shaft through the planetary gearing, auxiliary crank mechanism and link mechanism, and therefore, the time period. of non-productive or idle time in a cycle of operation can be substantially reduced whereby the slide can be displaced and returned at a fasted velocity as compared with the case of the slide movement in a prior artpress resulting in an increase of the number of strokes per minute.

Although one preferred embodiment of the present invention has been described and illustrated herein, it is to be understood that the same is illustrativein nature and not to necessarily limiting upon the scope of the teaching in its broader aspect.

What is claimed is:

1. A driving mechanism for the slide in a press comprising a main crank 'shaft rotatably journalled in the frame of said press for driving said slide, a main gear freely mounted on said. main crank shaft, a driving shaft journalled in said frame and having a fixed drive gear in engagement with said main gear for driving the latter, an auxiliary crankshaft journalled in said main gear, a planetary gear fixedly mounted on said auxiliary crank shaft and a sun gear fixedly supported in said frame in a concentric relation to said main crank shaft for engagement with said planetary gear, a crank pin of said auxiliary crank shaft being connected by means of a link to a fixed arm of said main crank shaft.

2. A'driving mechanism for the slide in a press as set forth in claim 1, in which said planetary gear rotates about its axis while the planetary gear revolves about said sun gear.

3. A driving mechanism for the slide in a press as set forth in claim 1, in which said sun gear and planetary gear have the same number of teeth and the planetary gear completes two rotations each time the main gear completes one rotation.

4. A driving mechanism for the slide in a press as set forth in claim 1, in which said auxiliary crank shaft completes two complete rotations each time said main gear of link mechanism to the main crank shaft in the form of an inequiangular rotational movement.

References Cited UNITED "STATES PATENTS Hembold et al. 74-394 Kawamura et al 74394 LEONARD H. GERIN, Primary Examiner 

